Field of the Invention
The present invention relates to an electronically commutated fan system, and especially relates to an electronically commutated fan system with a wide input voltage range of a three-phase and single-phase power source compatible application.
Description of the Related Art
Comparing with the conventional alternating-current fan (AC Fan), the electronically commutated fan (EC Fan) has the advantages of high efficiency, controllable rotational speed, applicable communication interfaces and multiple protection mechanisms. According to the basic principles of the motor, the rotational speed of the motor is dependent upon the input power source. Therefore, when the alternating-current input power source changes, the duty cycle is adjusted by the electronically commutated fan to maintain the stabilization of the rotational speed of the motor. However, if the variation of the alternating-current input power source is too large (for example, the voltage variation is over 100 volts) thus exceeding the range of steadily adjusting the rotational speed by adjusting the duty cycle, the rotational speed of the motor is still changed due to the variation of the alternating-current input power source, so that the rotational speed predetermined by the system cannot be achieved. Moreover, the voltage of the motor is deviated from the voltage of the original motor design which has the peak efficiency due to the variation of the alternating-current input power source, so that the efficiency of the motor is decreasing.
FIG. 1A shows a Y connection diagram of the related art motor. FIG. 1B shows a triangle (Δ) connection diagram of the related art motor. The related art three-phase electronically commutated fan has to have the differentiated design according to different alternating-current input power source due to the reasons mentioned above. Usually there are two methods: different motor winding design according to different voltage, or changing to different connection for the same motor. When the alternating-current input voltage is 3ψ220V, the triangle (Δ) connection shown in FIG. 1B is adopted. When the alternating-current input voltage is 3ψ380V, the Y connection shown in FIG. 1A is adopted. The methods mentioned above have different designs according to different three-phase input voltage (220V or 380V), so that the electronically commutated fan system mentioned above has following disadvantages:
1. A single three-phase electronically commutated fan system which is applicable to the voltage range of the wide input power source cannot be achieved. The related art electronically commutated fan has different motor winding design according to different voltage, or changes to different connection for the same motor, so that the three-phase electronically commutated fan with the wide input power source cannot be achieved.
2. The rotational speed of the electronically commutated fan system cannot achieve the predetermined rotational speed required by the cooling system. If the same fan is applied to the three-phase or single-phase power source, because the variation of the alternating-current input power source is too large thus exceeding the range of steadily adjusting the rotational speed by adjusting the duty cycle, the predetermined rotational speed cannot be achieved, so that the efficiency of the motor is decreasing.
3. The three-phase and single-phase power source compatible application cannot be provided. The related art electronically commutated fan does not have the three-phase and single-phase power source compatible application, so that the design of the cooling system or module lacks of the flexibility for the application of the power source.
Therefore, the inventors of the present invention would like to solve the problems mentioned above and would like to design an electronically commutated fan system which has the wide alternating-current input power source range, and which can maintain the stabilization of the rotational speed of the fan, and which can provide the three-phase and single-phase input compatible application.